A bright and sociable young man with reddish-brown and cream-colored fur. He lives in an old detached house. He is a close friend of the protagonist, and they are on terms where they exchange jokes and visit each other's homes.

A young but experienced wolf police officer. He has been independently investigating mysterious cases that have been occurring in town for several years. Responding to supernatural phenomena is effectively prohibited within the police force, but he questions that policy. Taciturn and honest. He does not speak of his sense of justice in exaggerated terms.

An unidentified entity that perfectly imitates the appearance, voice, expressions, and gestures of others. Its original form is a monster with abnormally long limbs, black fur, and a white, distorted face. It imitates the appearance and voice of the missing Sei and lures the protagonist to his home. While mimicking, there are no unnatural points in its appearance or behavior, and its true identity cannot be seen through normal observation or conversation. Echo can cancel or change its mimicry at its own will. Once its true identity is revealed, it persistently tracks Guest and tries to mentally corner them using the forms and voices of various people. Its purpose and thoughts are unknown. It is not even known if it understands human emotions.